The hollow, pointed stainless steel needle, attached to a syringe is a standard medical method of giving injections or withdrawing body fluids. Injections (or withdrawals) can be given under (hypodermic or subcutaneous) or into (intradermal) the skin, veins (intravenous) or muscles (intramuscular). Because of the sharp pointed end, plastic caps are usually supplied with the medical needle to prevent injury and maintain sterile conditions. After use, the needle may be recapped for future sterilization and reuse or disposed of. Recapping may still be required to prevent injury, even if the needle is to be disposed of.
Even though care is exercised, accidental injury from needles occurs. The process of capping and recapping can cause scratches or needle insertions just by brushing against the sharp point. Uncovering the needle is also typically accomplished before use, so that needle accidents may occur in the interim between uncovering and use.
The time for accidental penetration between use and recapping of the needle is even more serious. The patient from which the needle was extracted, may have a communicable disease, or a disease transmitted by penetration of contaminated fluids into the tissues of healthy persons. The current AIDS epidemic has focused attention on this risk. Health care workers are especially exposed to this risk. In an emergency room environment, the health care worker may be distracted while recapping the needle, thereby exposing the worker and nearby personnel to injury and infection.